This invention relates to boats, and in particular, to that part of a boat commonly known as a transom.
For practical purposes, the transom of a boat is the back of a boat, or a part of the back, more particularly that part of the boat to which the motor is attached in the case of an outboard motor, to which the so-called "stern drive" attaches in the case of a inboard/outboard arrangement or which, in other cases, merely serves as the rear wall of the boat. The invention has particular utility in relation to outboard motors and stern drive-boats an the term "transom" as used herein is to be understood as the rear portion of a boat to which the motor is attached.
As well known to those skilled in the art, when an outboard motor or stern drive is used to power a boat, it is attached to the transom by means of bolts. In essence, the outboard motor consists of a power head, a lower drive unit, means connecting the power head to the lower drive unit, and a bracket mechanism for mounting the whole assembly in relation to the boat. In this regard, the bracket is normally bolted to the transom so as to place the lower unit of the motor in proper position to thereby propel the boat with the propeller mounted on the lower unit. Similarly, with a stern drive, the lower unit extends from a housing attached to the transom.
Considering the above it will be apparent that it is common practice to drill the transom in order to permit the bolts to pass therethrough. Other items may commonly be mounted on the transom as well, but motor bolts are the most common cause for the so-called "drilling" of the transom.
In addition to exposing the transom's structure by virtue of the motor bolt holes drilled therethrough, it is noted that most boats are made in two parts, namely a bottom part and a top part. The bottom part of the boat, normally known as the hull, has the transom mounted at the rear end while the top part of the boat, normally called the deck, is attached to the hull. A seam is formed between the deck and the hull in the area of the transom and commonly this seam is formed in such a manner that it may have a tendency to leak.
In view of the potential for leaking at the joint between the deck and the hull in the area of the transom, and also the potential for leakage when holes are drilled through the transom for the motor bolts and the same are not thereafter properly sealed, it is quite common, as most outboard owners eventually realize, for transoms to rot. There is no way to determine the average life of a transom or its susceptibility to rot, because so much is dependent on the way the outboard motor is mounted, on what other holes may be made in the transom, on the way the transom is put together, and on the degree of sealing in the transom area between the deck and the hull. Suffice it to say, however, that rot in transoms is quite common in boats with power systems which require transom bolting.
In a traditional inexpensive boat, plywood pieces are bonded together to form a transom.
Regardless of the prior art transom structure used, the resulting product is usually adequate for a year or two. If the transom structure is properly sealed with silicone or other sealer so that water does not get to it when the motor holes are drilled or other items are installed on the transom, the same may last somewhat longer.
With the advent of the larger motors, the wood structure alone may be inadequate and the better boats have incorporated knee braces bonded between transom and stringers as well as metal reinforcing plates of one sort or another. To this end, any boat with reasonably high horsepower such as 140 or 150 HP engine or above should have both a plate on the outside of the boat and a plate on the inside of the splash well or inside of the transom to distribute the stresses from the motor throughout the entire transom area. Preferably at least one of these plates is folded as a right angle piece so as to minimize any tendency of the transom to bow.
While the use of metal reinforcements, and in fact the use of full inch and a quarter marine plywood tends to minimize any transom problems, those who have had a boat previously recognize that the metal plates and the wood transom are not ultimately the answer to any problem.
The problem is magnified as the horsepower attached to the boat increases and as the severity of conditions to which the boat is subjected increases. The larger the motor, the more strain on the transom, the more tendency there is for a slight flex. The more tendency there is for a slight flex, the more common the deterioration of the seals, and as the seals deteriorate, rot becomes a problem. The flex in the transom, particularly where wood is used, is not necessarily bad. Should anyone have a boat with some flex in it, it is improper to automatically assume that there is a defective transom. On the other hand, the potential for problems still exists more with larger horsepower motors because of the increased flex.
As well known to those skilled in the art, the structure of the hull of a fiberglass boat is composed of a series of fiberglass layers. The bottom of the hull is reinforced, in the normal instance, with a stringer system, balsa core, or other structure to accommodate the stresses put on it in use, and the transom of the boat carries a structure which is suited to support the motor. In essence, therefore, there is what might be deemed the basic structure of the boat, there is additional bottom support structure, and there is a different additional transom support structure. From the foregoing, it is therefore apparent that this invention applies to a boat having a hull in which there is a basic exterior structure, a reinforcing structure for the bottom of the boat, and a support structure in the transom of the boat for supporting the motor, and particular improvement concerns the structure in the transom of the boat for supporting the motor.